Current kcys radar loop shows isolated thunderstorms and showers east of the Laramie range this afternoon. Most of this activity has been weak thus far...with no persistent updrafts...and have been developing near surface outflow boundaries. Models indicate a weak cool front slowly moving southward into the area this afternoon...but current observations do not show any typical signatures of frontal passage. Observations further north do indicate winds shifting into the northeast up near Rapid City...so the cool front may be slower than models were showing earlier. This front will gradually push into far eastern Wyoming and the northern Nebraska Panhandle. This may result in thunderstorm activity lingering into late this evening.

Attention then shifts to the southwest tonight and Monday as the current watervapor satellite loop shows a vigorous upper level disturbance lifting northeast across the eastern Great Basin region. This shortwave will eventually move into Wyoming by Monday and linger through Tuesday. There is quite a bit of uncertainty in the track of this disturbance...since a track further north will result in dry windy conditions which may lead to fire weather concerns...while a track further south may result in numerous showers and thunderstorms across most of the forecast area with the potential of some severe thunderstorms. The GFS shows the driest solution...as the disturbance moves clockwise around southeast Wyoming through Tuesday. The other models are slower with the progression of this system...with the Gem the most aggressive showing widespread showers and thunderstorms across the southern two thirds of the forecast area...especially south of the Platte River valley. The new 18z NAM and sref are the slowest...showing this disturbance still over the forecast area through Tuesday night. Decided to focus mainly on Monday since there is limited confidence in Tuesday forecast...as it all depends on the specific track this disturbance takes. For Monday...pretty confident that areas west of the Laramie range will see at least a scattered coverage of showers and thunderstorms by the afternoon...and potentially lingering through Monday night as well. Increased pop between 30 to 70 percent along and west of i25...with lower values across the Nebraska Panhandle. With weak flow aloft...some of these thunderstorms may stall or drift very slowly. So there is a low flash flood concern. Temperatures will remain near or slightly above normal Monday with highs in the 80s to low 90s across western Nebraska.

An active quasi-zonal pattern will persist through the end of the week into the weekend. Models seem to be in better agreement today although still some slight timing differences are evident with shortwave features moving overhead through this time. Wednesday will see shortwave energy approach from the west...while surface winds veer from the north to the east-southeast across the plains through the afternoon and evening. Maintained at least slight chance for thunder over the mountains and from the Laramie valley eastward as monsoon moisture will accompany this wave. Could see some activity overnight across the plains as a stronger shortwave approaches during the overnight hours and maintains decent upslope flow. This wave will move over Wyoming and into the Dakotas/Nebraska by Thursday afternoon so the focus for lift and surface convergence...thus overall better shot for thunderstorms...will shift east into the Panhandle on Thursday.

Friday should remain mostly dry as a much drier airmass settles in behind the shortwave...although cant rule out an isolated storm or two in the afternoon over the higher terrain. Another plume of monsoonal moisture will combine with a shortwave trough on Saturday to bring increased chances for showers and thunderstorms over much of the County Warning Area through the day.

VFR conditions to prevail outside of thunderstorm activity. MVFR conditions are possible in moderate to heavy rainfall within thunderstorms this afternoon...with the highest confidence for kcys. Maintained thunderstorms in the vicinity elsewhere due to expected isolated coverage but will amend to prevailing thunderstorms and rain as necessary. Winds will remain relatively low with gusts up to 20 miles per hour at times across the plains through the afternoon. The exception will again be in and near thunderstorms where gusty erratic winds are likely.

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Fire weather... issued at 359 PM MDT sun Aug 2 2015

Fire weather concerns may become elevated on Tuesday after a quiet Monday. There is uncertainty of the track of an upper level trough and associated surface low across Wyoming on Tuesday. If this low takes a track further north...windy conditions are possible across most of southeast Wyoming and western Nebraska where gusts up to 40 miles per hour are possible. In addition...downslope winds will result in much lower relative humidities than what is currently forecast...mainly due to low confidence. Otherwise...a daily chance of showers and thunderstorms will continue through this week...especially over the High Plains. Relative humidities will remain between 15 to 25 percent...but wind speeds will be relatively light by late this week.